Rock drilling bit



AU8 30 19% R. "r. ALEXANDER 3,239,471

ROCK DRILLNG BIT Filed Nov 26. 1963 United States Patent O 3,269,411 ROCK DRILLIN G BIT Robert T. Alexander, P.(). Box 3, Columbia, Calif. Filed Nov. 26, 1963, Ser. No. 325,930 2 Claims. (Cl. 175--418) This invention relates in general to a rock drilling7 bit, and particularly to one of the percussion type adapted to be operated by a ja-ckhammer or similar mechanism.

The principal object of the present invention is to provide an improved rock drilling bit which embodies novel means for better removing the rock chips from the bore being drilled, so that the cutting edges of the bit will have a substantially clean or chip-free surface to cut against at all times.

A further object of the invention is to provide a rock drillingr bit, as above, wherein the chip removing means is arranged to that the gage ends of the cutting elements of the bit are protected from excessive wear.

With such chip removing means there results a faster drilling action and bore progress than possible with an ordinary rock bit, and the time consuming labor of continually sharpening the bit is avoided since the cutting edges remain sharp longer as they are largely kept clear of the abrasive action of the rock chips and dust.

The desired chip removing action is accomplished by the use of novel air passages in the bit and to which air under pressure is fed through the drill rod or shaft.

In connection With this feature, it is another object of the present invention to arrange the air passages in the bit in such a manner that while the rock chips at the bottom of the boreincluding the central area thereofwill be adequately removed, such passages do not interfere with the use of an unbroken full-Width cutting edge member on the bit. This makes it possible for the e-ntire area on the bottom of the bore to be cut without the use of an added small or secondary cutting member at the center of the bit.

A further object of the invention is to provide a rock drilling bit which is designed for ease and economy of manufacture.

A still further object of the invention is to provide a practical, reliable, and durable rock drilling bit and one which is exceedingly effective for the purpose for which it is designed.

These objects are accomplished by means of such structure and relative arrangement of parts as will fully appear by a perusal of the following specification and claims.

In the drawings:

FIG. 1 is a side elevation of the improved rock drilling bit.

FIG. 2 is a bottom plan view of the Same.

FIG. 3 is a sectional elevation of the bit in use; the view being taken on line 3-3 of FIG. 2.

FIG. 4 is a similar view but taken on line 4-4 of FIG. 2.

Referring now more particularly to the drawings and to the characters of reference marked thereon, the improved rock drilling bit, indicated generally at 1, is of the percussion type and includes a body 2 term-inating in an upward-ly projecting shank 3 of somewhat smaller diameter. The shank 3 is tapped, as at 4, to receive the correspondingly threaded end of the tubular drill rod or shaft 5 which extends from the operating mechanism for the bit.

Recessed into the body 2 at the bottom thereof is a diametrically extending cutting edge or bit member 6, the lower exposed portion of which is of V-shape in section with the opposed slopes shown at 7; such opposed slopes continuing across the body from the sides of member 6, as shown at 8. The cutting edge member 6, which 3 ,269,471 Patented August 30, 1966 is of extremely hard material, is here shown as being a single full-length piece but, if desired, may be made in two halves disposed in abutting relation.

Also recessed into the body 2 in opposed relation to the cutting edge member 6--and on opposite sides thereofare other diametrally alined cutting edge members 9 which extend from a junction with the sides of the member 6 to the periphery of the body, as clearly shown in FIG. 2. The cutting edge members 9 are of the same cross sectional shape and size as said member 6, and are on a level therewith.

The side of the body 2, lintermediate the outer ends of adjacent cutting edge members, is form-ed with vertical ilutes 10 of wide V-shaped form; the diametral size of the body .at the peripheral edge 11 between the flutes, and with which edge the outer ends of the cutting edge members are alined, approximating the size of the bore 12 made by the bit.

The central air passage 13 through the drill shaft 5 communicates at its inner end with a somewhat larger well 14 formed in the body 2 and terminating above the transverse recesses 15 therein and in which the cutting edge members 6 and 9` are seated.

A pair of relatively small passages 16 extend from the bottom of the well-adjacent the periphery thereofthrough the related portion of the body 2 and thence through the adjacent side edge portions of the cutting edge member 6 and the inner ends of the opposed cutting edge members 9. The exposed portions of said inner ends of the cutting edge members 9 are each cut on a bevel or slope 17 in symmetrical relation to and at substantially the same angle as the slope 7 of said member 6, as shown in FIG. 3.

Formed in the body 2 and projecting radially out from the side of the Well 14 at the bottom thereof to the per-iphery of the bit in alinement with the bottom of the body flutes 10 are passages, indicated generally at 19. These passages 19 are of small size relative to that of the well 14, and of substantially the same diameter as the passages 16. Tach passage 19 is formed with a short horizontal inner portion 20 leading from the well 14, and an outer portion 21 extending-at a sharp upward angleto the periphery of the bit shank 3 a short distance above the upper termination of the relatively large sized body 2 and the vertical V-shaped flutes 10 therein; the bottom of such flutes being in alinement w-ith the peripheral face of the shank 3, as clearly shown in FIGS. 2 and 4.

The outlet ends of the passage portions 21 are, of course, vertically elongated or oval as shown, and the lower ends of such outlets are rounded, as shown at 22, to eliminate the otherwise sharp edge ywhich might dig into any mud and the like when the bit is being retracted from the bore. The angle of said passage portions 21 is such as to give the most effective vacuum creating action when the bit is in use, as hereinafter described.

Operation When in use with the type of operating mechanism normally empolyed in connection with a percussion type bit, the bit is forcefully longitudinally vibrated or oscillated while being slowly rotated as it is advanced. With such action, air at a predetermined pressure is fed down the drill shaft 5 and into the well 1'4 of the body 2.

When the bit is momentarily clear of the bottom of the bore 12, air at common pressure will deliver through ythe passages 19 and 16. This causes blasts of air to be directed upwardly into the bore 12 about the bit and drill shaft from the passages 19, and-from the passages 16- radially of the bit at the bottom between the projecting portions of the intersecting cutting edge members 6 and 9 whereby the cuttings or chips made by the bit are forced from the central portion of the bottom of the bore 12 to the Zone of the flutes 10.

Upon the bit forcefully contacting and cutting into the bottom of the bore 12, the outlet ends of the passages 16 become substantially closed by contact with said bottom of the bore at the central portion thereof, and the air flow through said passages 16 is thus substantially, if not entirely, cut olf. This results in a greater and more forceful or higher pressure flow of air in the bore u-pwardly from the air passages 19, which in turn sets up or induces a reduction of pressure or tendency to vacuum in the bore area below the outlets of said passages 19. Consequently, the loose cuttings or chips previously delivered to the lower ends of the flutes w-ill be drawn up into the above described upwardly moving and relative-ly high pressure air stream and ultimately carried out lof the bore 12.

The above recited cycle will, of course, be recurringly repeated as the bit longitudinally v-ibrates or oscillates during its bore drilling action. The angle of the passages 1'9 being as steep as possible, the streams of air issuing therefrom move upwardly with a minimum of resistance from the wall of the bore 12 and as such streams are between the outer gage ends of the eutt-ing edge members of the bit, the loose air-borne cuttings or chips are drawn away from Such ends and wear thereon is reduced.

The passages 16, being in off-center relation to the axis of the bit, revolve with the bit in an orbit around the center thereof. This allows one cutting edge member or the other to extend across the center of the b-it without a break, so as to drill or cut out the central porti-on of the bottom of the bore 12, and without the need of an additional small central cutting bit.

From the foregoing description, it will be readily seen that there has been produced such a device as substantially fulfills the `objects of the invention, as set forth herein.

While this specification sets forth in detail the present and preferred construction of the device, still in practice such deviations from such detail may be resorted to as do not form a departure from the spirit of the invention, as dened by the appended claims.

Having thus descnibed the invention, the following is claimed as new and useful and upon which Letters Patent lis desired:

1. A percussion type rock drilling bit comprising a generally cylindrical body having an upwardly projecting relatively small diameter shank adapted for connection with a tubular drill shaft having air under pressure therein, a full width transversely extending cutting edge member mounted on and depending from the bottom of the body, a well in the body in communication with the drill shaft at the lower end thereof, relatively small air passages extending in the body from the 4bottom of the well to the bottom of the body at the sides of and adjacent the cutting edge member, other similar sized air passages in the body leading from the s-ide wall of the well adjacent the bottom thereof, said other passages having outer portions disposed at a Steep upward slope and terminating at the periphery of the shank on opposite sides of the corresponding ends of the cutting edge member, and vertical open-ended flutes in the side of the body and alined with the peripheral terminations of Said other passages.

2. A percussion type rock drilling bit comprising a generally cylindrical body having an upwardly projecting relatively small diameter shank adapted for connection with a tubular drill shaft having air under pressure therein, a transversely extending cutting edge member mounted on and depending from the bottom of the body, vertical open-ended flutes in the periphery of the body on opposite Sides of the cutting edge member at the ends thereof, and relatively small air passages in the body in communication with the interi-or of the drill shaft at the lower end thereof; portions of said passages inclined upwardly at a steep angle to the axis of the shank to outlet openings at the periphery thereof in alinement w-ith the bottom of the utes adjacent the upper ends thereof, and said outlet open-ings being rounded at the bottom.

References Cited by the Examiner UNITED STATES PATENTS 542,542 7/1895 Symonds 175-418 X 735,769 8/1903 Higgins 175-418 2,879,973 3/1959 saxman 175-418 X 3,011,571 12/1961 DeBree et a1 175-418 x CHARLES E. OCONNELL, Primary Examiner.

N. C. BYERS, Assistant Examiner. 

1. A PERCUSSION TYPE ROCK DRILLING BIT COMPRISING A GENERALLY CYLINDRICAL BODY HAVING AN UPWARDLY PROJECTING RELATIVELY SMALL DIAMETER SHANK ADAPTED FOR CONNECTION WITH A TUBULAR DRILL SHAFT HAVING AIR UNDER PRESSURE THEREIN, A FULL WIDTH TRANSVERSELY EXTENDING CUTTING EDGE MEMBER MOUNTED ON AND DEPENDING FROM THE BOTTOM OF THE BODY, A WELL IN THE BODY IN COMMUNICATION WITH THE DRILL SHAFT AT THE LOWER END THEREOF, RELATIVELY SMALL AIR PASSAGES EXTENDING IN THE BODY FROM THE BOTTOM OF THE WELL TO THE BOTTOM OF THE BODY AT THE SIDES OF AND ADJACENT THE CUTTING EDGE MEMBER, OTHER SIMILAR SIZE AIR PASSAGES IN THE BODY LEADING FROM THE SIDE OF THE WELL ADJACENT THE BOTTOM THEREOF, SAID OTHER PASSAGES HAVING OUTER PORTIONS DISPOSED AT A STEEP UPWARD SLOPE AND 